The pages feel thinner and you can see the text on the other side more as well. Book 6 is a 10th printing and book 7 is a 5th printing. Doesn’t say years, so I wonder if they switched to thinner or back to thicker?
Interesting, and this could make sense. I checked book 8, it’s about the same thickness as 7, but 200 pages shorter. So it’s the thicker pages again, first edition, dunno if they’ve done a second yet as it’s new.